Electric cord stress relief combined with a strain relief grommet

ABSTRACT

A stress relief is integrally joined to a strain relief bushing providing a spaced-away hold to a line cord providing an axis of movement relieving wire stress movement.

United States Patent 11 1 1111 3,749,818

Jemi son I 1 1 July 31, 1973 1 ELECTRIC CORD STRESS RELlEF 1,210,29012/1916 Feick 339/103 R COMBINED WITH A STRAIN RELIEF :11: 29 3% 4 3umpp, r.

GROMMET 3,122,386 2/1964 Pearson 174/135 ux [75] Inventor: WilliamJemison, Summit, NJ. 3,493,205 2/ 0 B om g /153 G X 3,516,111 6/1970Heyman 16/2 Asslgnee= "W Manufmumlg Company, 3,622,942 11/1971 Rynk339/107 Kenilworth, N]. R P l S FOREIGN PATENTS 0 AP L CATION [22] 1971216,606 8/1961 Austria 174/153 G 21 App]. No.: 185,314 V 1,159,5367/1969 Great Britain 339/10 52 us. Cl 174/153 1;, 16/2, 248/56 PrimaryExaminer-Laramie Askin 51 Im. Cl F161 5/00, l-lOlb 17/26 Arthur Slanderet [58] Field of Search 174/65 G, 135, 152 G,

174/153 G; 16/2; 248/56; 339/101, 103 R, [57] ABSTRACT A stressrel1ef1s1ntegra1ly omed to a stram rel1ef bush- [56] References Citd ingproviding a spaced-away hold to a line cord provid- UNITED STATESPATENTS ing an axis of movement relieving wire stress movement.3,701,505 10/1972 Klumpp, Jr. 174/153 G X 3,617,615 11/1971 Balzer339/107 X 21 Claims, 15 Drawing Figures Pmmiu v 3.749.818 sum 1m 4INVENTOR. Mun/11 JEu/sav PAIENIEB l 3 1 ms sum 2 or 4 INVEN TOR.

Mil/4M A m/50M W JJMM ELECTRIC CORD STRESS RELIEF COMBINED WITH A STRAINRELIEF .GROMMET The present invention relates to a novel stress reliefpreferably combined with a strain relief bushing.

Common devices for stress relief in the past were springs or otherencircling devices seen onitems such as electric iron plugs or toasterplugs. Other devices achieved the same result by supporting electriccords by various means along their length or at their stress point ornatural bending point.

The need for such stress relief was necessitated by the fact thatelectric cords or wires which were bent or bendable at a particularpoint or axis were likely to wear or have their wires cracked byfatigue.

The normal protection afforded a cord by even a usual bushing or strainrelief bushing did not change the axis of wire bending, such as at aplug end. Such bending usually resulted in worn or frayed wires in ashort period of time.

One of the most successful ways of solving the problem of stress frayingor wear was by using elongated encircling springs. Such springs providedsupport to a cord and made gentle, if any bend on the cord, andprevented a focus of such bend on a vulnerable point such as the pointof exit of'a cord from a toaster plug.

It was often found advantageous to bombine stress relief with strainrelief. Strain relief protected a'cord against being pulled at itspoint'of attachment.

As can be seen, devices such as the encircling springs were expensiveand required labor to assemble and other devices were among otherthings, expensive or awkward to use.

According to the present invention, a new stress relief, preferably of adielectric plastic is provided integral to a bushing or bushing assemblyand in a preferred embodiment made in combination with a strain reliefbushing. Although such novel feature or features believed to becharacteristic of the invention are pointed out in the claims, theinvention and the manner in which it may be carried out may be furtherunderstood by reference to the description following and theaccompanying drawings. 7

FIG. I is a cut-away isometric view of a stress relief and bushing ofthe present invention in use.

FIG. 2 is a plan view of the stress relief and bushing of FIG. I.

FIG. 3 is a side elevation of the stress relief and bushing of FIG. 1.

FIG. 4 is a plan view of another embodiment of the stress relief andbushing of the present invention.

FIG. 5 is an exploded plan view of another stress relief and bushing.

FIG. 6 is a plan view of another embodiment of the stress relief andbushing of the present invention.

FIG. 7 is a side elevation of the stress relief and bushing of FIG. 6.

FIG. 8 is a plan view of another stress relief and bushing of thepresent invention.

FIG. 9 is a plan view of another stress relief and bushing of thepresent invention. I

FIG. 10 is a plan view of another stress relief and bushing of thepresent invention.

FIG. 11 is a side view of another stress relief and bushing of thepresent invention engaging an electric cord.

FIG. 12 is a plan view of the embodiment of FIG. 1 1.

FIG. 13 is another embodiment of the stress relief and bushing of FIG.11. 7

FIG. 14 is a side elevation of another stress relief and bushing of thepresent invention.

FIG. 15 is the stress'relief andbushing of FIG. 14 engaged on a cord.

Referring to the figures in greater detail, where like reference numbersdenote like parts in the various figures.

The stress relief 10 and strain relief bushing 9 as shown in FIGS. 1 3comprise a strain relief grip block 11, a shank 12, the gripblock 11 andshank 12 joined j 1 by a webbing 13 which includes the stress relief 10.

The webbing 13 comprises arms l4, 15 or straps which extend to a supportring 16 having an opening 17. The opening 17, as shown in FIGS. I 3includes anexternal collar 18.

In the embodiment of the stress relief 10, strain relief bushing 9, asshown in FIGS. 1 3, the grip block 11 includes a-tongue l9 which fitsinto a pair of channel tracks 20 which extends into a recess 21 in. theshank 12. The tracks 20 extend-inward between the lips 22, 23 so thatwhena cord 24 of proper, selected size is placed lengthwise in the shank12, the placing of the grip block 11, tongue 19 in the channel tracks 20will tend to crease the cord 24.

The grip block 1 1 includes a recess 25 substantially aligned with arecess 26, thus when a cord 24 is engaged in the shank l2 and the gripblock 11, tongue l9 is engaged in the channels 20, the placing of thegrip block 11 and shank l2 in an'aperture 27 causes the tongue 19 tokink the cord 24. The grip block 11 includes a ramp 28. The shank 12includes a ramp 29.

In use as a stress relief 10, as shown in FIG. 1, an

electric cord 24 is positioned in the opening 17 which has a collar 18extending a selected distance, thecord 24 is then placed in the strainrelief bushing 9 and the wire 24, stress relief 10 and bushing 9 arethen engaged. When the grip block 11 and shank 12 are inserted into theaperture 27, the grip block 11 and shank 12 are forced together by theramp 28, 29 until the wall of the aperture 27 is engaged in the recesses25,26 holding the bushing 9 in the aperture 27 with the tongue 19kinking the cord 24. At this point, the bush ing 9 is held firmly in theaperture 27. Any strain on the cord 24 is taken by the bushing and theaperture 27 since the tongue 19, grip block 11 and shank 12 all movetoward the wall of the aperture 27 containing longitudinal stress at thebushing 9 in the aperture.

With the bushing 9 engaged in the aperture 27, the stress relief 10provides a flexible grip engirdling the cord 24 spaced away from theface of the grip block 1 l and shank 12. This spacing away in effectforms a bending radius 30 the distance between the face of the bushing 9and the furthest extenfof the stress relief 10 so that any bending ofthe cord 24 engirdled by the stress relief 10 is not at the face of thebushing 9, but extending along a greater distance than a strain reliefalong would support, that is, the distance from the radius 30 the collar18. p

The angulation of the straps or arms 14, 15 tangent to the support ring16 of the webbing13 helps facilitate tortional movement and lateralmovement. The support ring 16 is substantially intermediate of the arms14, 15. The grip block 11, shank 12 and webbing 13 are substantiallyaligned. I

It is preferable to have the stress relief and bushing 9 integrallymolded.

The stress relief 40 as shown in FIG. 4 is integral with a grip block 11 and shank 12. The webbing 41 holds the support ring 16 spaced apartfrom the grip block 11 and shank 12 by two pairs of arms 42, 43 whichtaper toward the support ring 16. The arms 42 from the grip block 11extend from an extended yoke 44.

The stress relief 40 and bushing 9 function in use substantially as thestress relief 10 and bushing 9 as disclosed in FIGS. 1 3.

The stress relief 80 as shown in FIG. 8 is exemplified with the gripblock 11 and shank 12. The webbing 81 of the stress relief 80 comprisesa tapered arm 82 from the grip block 1 1 to the support ring 16 andanother tapered arm 83 from the shank 12 to the support ring 16. Thetapering of the arms 82, 83, narrowing at the support ring 16, tends togive a spring-like resilience to the stress relief 80. The stress relief80 with the bushing 9 otherwise functions substantially as describedwith regard to FIGS. 1 3.

The stress relief 90, as shown in FIG. 9 is exemplified with the gripblock 11 and shank 12. The webbing 91 comprises arms 92, 93 extendingfrom the shank 12 angling to the support ring 16 and a single arm 94extending from the center of the grip block 11 to the support ring 16.The stress relief 90 construction provides the flexibility of havingarms 92 94 to support the support ring 16 from three directions whileavoiding a complicated construction extending from the grip block 11.

The stress relief 50, as shown in FIG. 5, is exemplified in use with abushing 9 having a grip block 11 and shank 12. The grip block 11 has aprotruding tongue 51. The shank 12 has protruding tongues 52, 53, 54.

The shank 12, tongues 52, 53, 54 protrude from the bottom of the shank12 face and both sides. When the grip block 11 is engaged, the tongue 51protrudes forward providing a stress relief surrounding cord 24. Asshown, the tongues 51 54 are tapered, thus a cord 24 may have somemovement beyond the radius 55, the distance between the face of thebushing 9 and the end of the tongues 51 54 by movement between thetapered tongues 51 54.

The stress relief 60, as shown in FIGS. 6 and 7, has the grip block 1 1and shank 12 attachedto the arms 61, 62 respectively. The webbing 59comprising arms 61, 62 supports the ring 16. The face of the shank 12-has a pairof tongues 63, 64 opposite each other and a right The stressrelief 110, as shown in FIGS. 11 and 12,

is also combined with a strain relief bushing 1 1 1 having a grip block11 and a shank 12. The grip block 11 and shank 12 are joined by a strap1 12. Insofar as a bushing 111 is concerned, its function issubstantially the same as the bushing 9 with the grip block 11 and shank12 interlocking to grasp a cord 24.

The stress relief includes a pair of arms 113, 114, extending outward,and supporting a plate 115. The arms 113, 114 are preferably slightlytapered, the plate 1 15 preferably includes notches 1 16, 1 17 inward ofthe outer periphery of the plate 115. The plate 115 has a small centralopening 118 and is divided into tapering segments 1 19.

Thus, as can be seen in FIG. 11, a cord 24 passing through the opening118 will have the segments 119 accommodate themselves to the size of thecord 24 and hold the cord in a spring grasp. The closed bushing 11 1 isheld in an aperture 27 while the arms 113, 114 flex with the plate 115,holding the cord 24 to relieve stress. The webbing 120 as shown in FIGS.11 and 12, is free and independent of the grip block 1 1. The notches116, 117 half form a bending axis for the plate 115.

In FIG. 13 a stress relief has a webbing 131, comprising a pair of arms132, 133 extending from a shank 12 and tapering to a point where thearms 132, 133 join a plate 134. The plate 134 has no specially definedopening, but does have segments 135 functionally similar to the segments119 as shown in FIGS. 11, 12.

A grip block 11 is joined to the other end of the plate 134 by an arm136.In use, the stress relief 130 provides three support arms 132, 133,136 holding the plate 134, providing stress relief to the cord 24.

In FIG. 14, the stress relief 140 and bushing 9have a webbing 141extending between the grip block 11 and shank 12. The arms 142, 143 meetthe support ring 144 from the underside. Thus, the support ring 144 ison a different plane from that of the arms 142, 143..

The curves 145, 146 allow the stress relief 140 to maintain asubstantially longitudinal position when not in use.

angle to the arms 61, 62. Thus, when the stress relief 50 serted in theopening 17, then the grip block 104 is. folded into the second shanksection 103, folded on thev strap 105. The bushing 101 is then closed,the ears 106 locking on the detents 107. The stress relief 100 performsits normal function. The cord 24 is given strain relief by the cammingaction between the camming grip block 104 and the cam surface inside thesecond shank portion 103.

The curves 145, 146 provide a greater stress relief distance over ashorter longitudinal length of stress relief 140 and bushing 9 since thecurves 145, 146 are functional in providing length to the arms 142, 143,i

when in the shank 12 and grip block 11, as shown in FIG. 15, yet thecurves 145, 146 do not further space apart the shank 12 and grip block11 when they are in a longitudinal position.

The width of the support ring 144 may further extend the distance ofstress relief support for the cord 24 from the outer edge of the supportring 144 to the face of the shank 12 and bushing 9.

As shown in FIG. 15, the cord 24 in the support ring 144 and with theshank 12 and gripblock 11 closed, tends to get further support. The arms142, 143 bow inward from the curves 145, 146 and tend to hug the cord24. This hugging is both supportive and generally more acceptable to aconsumer of a toaster plug, for instance, who might not understand theabsence of the usual wire spring.

No sizes nor dimensions have been described since the stress reliefsshown in the present application must be selected by those skilled inthe art to determine the requisites for the various diameter and shapedcords, the necessary length each cord and type of cord must be held awayfor a proven radius for stress relief. Also,

there is the question of which stress relief is best suited for aparticular usage.

The terms and expressions which are employed are used as terms ofdescription; it is recognized, though, that various modifications arepossible.

Having thus described certain forms of the invention in some detail,what is claimed is: g

1. In combination with a strain relief bushing adapted to hold anelectric cord in an aperture, said strain relief bushing including ashank portion and grip block portion, said shank portion and grip blockportion interfitting and adapted to kink said cord, integral stressrelief means including a webbing; said webbing extending from both saidshank and said grip block parts; said webbing including an integralengirdling means substantially intermediate thereof for said electriccord; said engirdling means being open therethrough; said webbing alsocomprising strap means in the form of arms retaining said engirdlingmeans; said strap means extending a selected distance from said strainrelief bushing to said engirdling means; said strap means and saidengirdling means when engaged with said electric cord enabling movementfor said electric cord substantially spaced apart from said strainrelief bushing, said strap means supporting said engirdling means at aposition spaced away from said strain relief bushing.

2. The invention of claim 1, wherein said strap means joins saidengirdling means at a tangent, and said webbing is adapted for torsionalmovement when engaged with said electric cord.

3. The invention of claim 1 wherein saidstrap means are joined inward ofthe periphery of said engirdling means.

4. The invention of claim 3 wherein said engirdling means extends beyondthe width of said strap means.

5. The invention of claim 3 wherein said strap means joins saidengirdling means at a curve from said strap means.

6. The invention of claim 1 wherein said strap means extend from theouter periphery of said engirdling means.

7. The invention of claim 1 wherein said strap, means tends to bowinward when said strain relief portions are in closed position.

8. The invention of claim 1 wherein said strap means are substantiallyparallely aligned.

9. The invention of claim 8 wherein said strap means taper toward saidengirdling means.

10. The invention of claim 1 wherein at least one part of said strainrelief bushing includes at least one electric cord supporting tongue.

1 l. The invention of claim '1 including more than two strap means.

12. The invention of claim 11 wherein at least two said strap meansconverge toward said engirdling means. I

13. The invention of claim 12 wherein four said strap means convergetoward said engirdling means.

14. The invention of claim 11 including three strap means.

15. The, invention of claim 14 wherein said engirdling means comprises aplate including segments.

16. The invention of claim 1 wherein said engirdling means comprises aplate including segments.

17. The invention of claim 1 wherein said strain relief bushing includesmore than two parts.

18. In combination with a strain relief bushing adapted to hold anelectric cord in an aperture, the said strain relief bushing including ashank portion and grip block portion, said shankiportion and grip blockportion interfitting and adapted to kink said electric cord,

said tongues is tapered.

1. In combination with a strain relief bushing adapted to hold anelectric cord in an aperture, said strain relief bushing including ashank portion and grip block portion, said shank portion and grip blockportion interfitting and adapted to kink said cord, integral stressrelief means including a webbing; said webbing extending from both saidshank and said grip block parts; said webbing including an integralengirdling means substantially intermediate thereof for said electriccord; said engirdling means being open therethrough; said webbing alsocomprising strap means in the form of arms retaining said engirdlingmeans; said strap means extending a selected distance from said strainrelief bushing to said engirdling means; said strap means and saidengirdling means when engaged with said electric cord enabling movementfor said electric cord substantially spaced apart from said strainrelief bushing, said strap means supporting said engirdling means at aposition spaced away from said strain relief bushing.
 2. The inventionof claim 1, wherein said strap means joins said engirdling means at atangent, and said webbing is adapted for torsional movement when engagedwith said electric cord.
 3. The invention of claim 1 wherein said strapmeans are joined Inward of the periphery of said engirdling means. 4.The invention of claim 3 wherein said engirdling means extends beyondthe width of said strap means.
 5. The invention of claim 3 wherein saidstrap means joins said engirdling means at a curve from said strapmeans.
 6. The invention of claim 1 wherein said strap means extend fromthe outer periphery of said engirdling means.
 7. The invention of claim1 wherein said strap, means tends to bow inward when said strain reliefportions are in closed position.
 8. The invention of claim 1 whereinsaid strap means are substantially parallely aligned.
 9. The inventionof claim 8 wherein said strap means taper toward said engirdling means.10. The invention of claim 1 wherein at least one part of said strainrelief bushing includes at least one electric cord supporting tongue.11. The invention of claim 1 including more than two strap means. 12.The invention of claim 11 wherein at least two said strap means convergetoward said engirdling means.
 13. The invention of claim 12 wherein foursaid strap means converge toward said engirdling means.
 14. Theinvention of claim 11 including three strap means.
 15. The invention ofclaim 14 wherein said engirdling means comprises a plate includingsegments.
 16. The invention of claim 1 wherein said engirdling meanscomprises a plate including segments.
 17. The invention of claim 1wherein said strain relief bushing includes more than two parts.
 18. Incombination with a strain relief bushing adapted to hold an electriccord in an aperture, the said strain relief bushing including a shankportion and grip block portion, said shank portion and grip blockportion interfitting and adapted to kink said electric cord, integralstress relief means including a plurality of tongues for surroundingsaid electric cord, said tongues attached to and extending a selecteddistance from said strain relief bushing, said tongues being forproviding a stress relief for said electric cord.
 19. The invention ofclaim 18 wherein said tongues are substantially evenly spaced about saidstrain relief bushing.
 20. The invention of claim 18 wherein at leasttwo pieces of said strain relief bushing include said tongues.
 21. Theinvention of claim 18 wherein at least one of said tongues is tapered.